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Sleep-laughing – Hypnogely

Published online by Cambridge University Press:  23 September 2014

Nikola N. Trajanovic*
Sleep Research Unit, University Health Network Neurophysiology Unit, Polyclinic ‘Dr. Ristic’
Colin M. Shapiro
Sleep Research Unit, University Health Network Department of Psychiatry, University of Toronto, Toronto, Canada
Srdjan Milovanovic
School of Medicine, Belgrade University Clinic for Psychiatry, Clinical Centre of Serbia, Belgrade, Serbia
Sleep Research Unit, UHN TWH MedWest, 221-750 Dundas St. W., Toronto, Ontario, M6J 3S3, Canada. Email:
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To explain relatively common phenomenon of laughing during sleep and help to better define criteria for differentiating between physiological and pathological sleep-laughing.


Observational study of patients who underwent a sleep assessment in a referential tertiary health facility.


A total of ten patients exhibited sleep laughing, nine of whom had episodes associated with rapid eye movement (REM) sleep. Also, in one of the patients sleep-laughing was one of the symptoms of REM sleep Behaviour Disorder, and in another patient sleep-laughing was associated with NREM sleep arousal parasomnia.


The collected data and review of literature suggests that hypnogely in majority of the cases presents as a benign physiological phenomenon related to dreaming and REM sleep. Typically, these dreams are odd, bizarre or even unfunny for a person when awake. Nevertheless, they bring a sense of mirth and a genuine behavioural response. In a minority of cases, sleep-laughing appears to be a symptom of neurological disorders affecting the central nervous system. In these patients the behavioural substrate differs when compared to physiological laughing, and the sense of mirth is usually absent.

Research Article
Copyright © The Canadian Journal of Neurological 2013


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